This project proposes to do an in-depth evaluation of patients with Meniere's disease from the audiological, auditory physiological and vestibular standpoints. Cochlear function will be qualified using routine audiometry, electrocochleography, auditory brain-stem responses, and otoacoustic emissions in a pre-and postglycerol ingestion paradigm. Vestibular function will be quantified using computerized measures of vestibulo-ocular and vestigulospinal reflexes. Patients will be randomized into two groups: 1) endolymphatic sac-mastoid shunting and 2) controls. Long term follow-up will use same measures with occasional glycerol challenges over a two year period. By systematically applying these objective measures of cochlear and vestibular function, we should be able to 1) reliably group patients with Meniere's disease into various categories according to sites of involvement of the end organ, i.e., sensory hair cells vs neural elements, and 2) define the diagnosis and natural course of the disease and test the validity of the endolymphatic sac-mastoid shunt. Ultimately, it should be possible to outline objective indicators that can predict success of various treatments in this disease.